In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more...In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more efficient among the renewable energy sources. The penetration level of variable-speed wind turbines continues to increase. The interconnected wind turbines, however, have no inertia and no synchronous power. Such devices can have a serious impact on the transient stability of the power grid system. One solution to stabilize such grid with renewable energy sources is to provide emulated inertia and synchronizing power. We have proposed an optimal design method of current control for virtual synchronous generators. This paper proposes an optimal control method that can follow the virtual generator model under constrains. As a result, it is shown that the proposed system can suppress the peak of the output of semiconductor device under instantaneous output voltage drop.展开更多
In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as t...In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.展开更多
A new fault identification method, which is called the apparent current method, based on the parameter variation of apparent current is proposed after the analysis of the limitations of the fault interpretation method...A new fault identification method, which is called the apparent current method, based on the parameter variation of apparent current is proposed after the analysis of the limitations of the fault interpretation method for the wide field electromagnetic data in the non-seismic exploration for oil and gas exploration. This method takes the study of the wide field electromagnetic theory and the mechanism of the fault generation, this method takes the wide field electromagnetic data as the research object, and establishes the connection between the geoelectric section and the virtual equivalent circuit, and then uses the virtual equivalent circuit as the carrier, and applies the theoretical equation of the apparent current, and combines the geological background of the study area to achieve scientific inference for location of fault in wide field electromagnetic exploration data. Theoretical model tests and the application of practical data proved that the location of underground fault can be accurately deduced by the trend of apparent current in underground space, reducing the multiple interpretations of electromagnetic data interpretation. At the same time, it also verified the correctness of the theory of apparent current and the feasibility of the method of apparent current.展开更多
Sparse measurements challenge fault location in distribution networks.This paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vec...Sparse measurements challenge fault location in distribution networks.This paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).The relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint the fault.Furthermore,a two-stage recovery strategy is proposed for improving reconstruction accuracy of the current vector,where two different sensing matrixes are utilized to improve the incoherence.The proposed method is validated in IEEE 34 node test feeder.Simulation results show asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our method.In addition,it works effectively under various scenarios of noisy measurement and line parameter error.Validations on 134 node test feeders prove the proposed method is also suitable for systems with more complex structure.展开更多
文摘In recent years, power generation using renewable energy sources has been increasing as a solution to the global warning problem. Wind power generation can generate electricity day and night, and it is relatively more efficient among the renewable energy sources. The penetration level of variable-speed wind turbines continues to increase. The interconnected wind turbines, however, have no inertia and no synchronous power. Such devices can have a serious impact on the transient stability of the power grid system. One solution to stabilize such grid with renewable energy sources is to provide emulated inertia and synchronizing power. We have proposed an optimal design method of current control for virtual synchronous generators. This paper proposes an optimal control method that can follow the virtual generator model under constrains. As a result, it is shown that the proposed system can suppress the peak of the output of semiconductor device under instantaneous output voltage drop.
文摘In recent years, power generation using renewable energy sources has been developed as a solution to the global warming problem. Among these power generation methods, wind power generation is increasing. However, as the penetration level of wind power generation increases, the low inertia and lack of synchronous power characteristics of the penetrated power system can have a significant impact on the transient stability of the grid. The virtual synchronous generator provides the ability of virtual inertia and synchronous power to interconnected inverters. The interconnected inverter with the virtual synchronous generator ability uses, in general, PI control based current controller. This paper proposes a new current-control method and compares it with conventional methods. The proposed current control is a method that follows virtual synchronous generator model that changes every moment by solving the discrete-time linear quadratic optimal control problem for each sampling time interval. The new method follows the conventional method, and therefore the reactive power fluctuation can be suppressed and the interconnected inverter will be downsized.
基金Supported by the Petro China Science and Technology Major Project(2017E-11)
文摘A new fault identification method, which is called the apparent current method, based on the parameter variation of apparent current is proposed after the analysis of the limitations of the fault interpretation method for the wide field electromagnetic data in the non-seismic exploration for oil and gas exploration. This method takes the study of the wide field electromagnetic theory and the mechanism of the fault generation, this method takes the wide field electromagnetic data as the research object, and establishes the connection between the geoelectric section and the virtual equivalent circuit, and then uses the virtual equivalent circuit as the carrier, and applies the theoretical equation of the apparent current, and combines the geological background of the study area to achieve scientific inference for location of fault in wide field electromagnetic exploration data. Theoretical model tests and the application of practical data proved that the location of underground fault can be accurately deduced by the trend of apparent current in underground space, reducing the multiple interpretations of electromagnetic data interpretation. At the same time, it also verified the correctness of the theory of apparent current and the feasibility of the method of apparent current.
基金supported in part by Key-Area Research and Development Program of Guangdong Province(No.2020B010166004)State Key Program of National Natural Science Foundation of China under Grant(No.U1866210)Natural Science Foundation of Guangdong Province(No.2022A1515011587).
文摘Sparse measurements challenge fault location in distribution networks.This paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).The relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint the fault.Furthermore,a two-stage recovery strategy is proposed for improving reconstruction accuracy of the current vector,where two different sensing matrixes are utilized to improve the incoherence.The proposed method is validated in IEEE 34 node test feeder.Simulation results show asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our method.In addition,it works effectively under various scenarios of noisy measurement and line parameter error.Validations on 134 node test feeders prove the proposed method is also suitable for systems with more complex structure.
